JP2003227318A - Lash adjuster in valve system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce manufacturing costs of lash adjuster using buttress threads. <P>SOLUTION: An adjust screw 15 is screw-engaged to a screw hole 14 of a nut member 13 arranged on a lower face of an end plate 12 of a lifter body 11. The adjust screw 15 is pressed in a shaft direction by an elastic body 16. A female screw 14a of the screw hole 14 and a male screw 15a of an outer peripheral of the adjust screw 15 are formed to have buttress threads. The nut member 13 is assembled so that it contacts the lower face of the end plate 12 and the nut member 13 is pressed to the lower face of the end plate 12 by pressing force of an elastic member 19. The manufacturing cost can be reduced as the nut member 13 is whirl-stopped by contacting with the lower face of the end plate 12. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lash adjuster for automatically adjusting the valve clearance of a valve train in an internal combustion engine.

[0002]

2. Description of the Related Art In a valve operating system that opens and closes an intake valve or an exhaust valve (hereinafter simply referred to as a valve) by rotating a cam, a valve clearance is automatically adjusted by incorporating a lash adjuster.

As the lash adjuster of this type, the applicant of the present application has already proposed a screw type lash adjuster which can reduce the axial length of the valve train and is easy to assemble with a small number of parts ( Japanese Patent Laid-Open No. 11-3
24617 and JP-A-11-324618).

In the lash described in the above publication, as shown in FIG. 7, a nut member 13 'is provided on the lower surface of an end plate 12' provided on the upper side of a lifter body 11 ', and a screw hole of the nut member 13' is provided. The adjusting screw 15 'screwed into the screw hole 14' is axially pressed by the elastic body 16 'incorporated in the closed end of the screw hole 14', and the internal screw 14a 'of the screw hole 14' and the adjusting screw 15 'are pressed. '
The external thread 15a 'formed on the outer circumference of the outer peripheral surface of the idle side is formed with the flank angle of the pressure side flank 17' that receives the pushing load applied to the adjusting screw 15 '.
It has a sawtooth shape larger than the flank angle of 8 ', and the sawtooth thread is provided with a lead angle at which the adjusting screw 15' is axially moved while being rotated by the pressing of the elastic body 16 '.

The lash adjuster having the above-described structure is, for example, as shown in FIG. 1, a cam 1'and a valve 5 '.
Installed between the valve stems 2'provided in the valve stem 2 ', the end face of the valve stem 2'is pressed against the end face of the adjusting screw 15' by the elastic force of the valve spring 4'which presses the valve stem 2'to the cam 1'side, and the pressing The force is transmitted to the cam 1'through the lifter body 11 ', and the cam 1'
The valve 5'is opened and closed by the rotation of.

When the lash adjuster is assembled as described above, the valve stem 2'and the adjusting screw 1
When valve clearance occurs between 5 ', elastic body 16'
Due to the pressing force of the adjusting screw 15 ', the adjusting screw 15' moves in the axial direction while rotating along the idle flank 18 'to absorb the valve clearance.

When the adjusting screw 15 'receives a pushing force by the valve stem 2', the female screw 14 '
a'and the male screw 15a ', the adjusting screw 15' is retracted until the axial screw gap formed in the screw engaging portion is closed, and when a pushing force is applied, the pressure side flanks 16 'are pressed against each other to cause the above. This prevents the adjusting screw 15 'from moving backward while rotating due to the pushing force.

Here, in the case of a fluctuating load in which the pushing load applied from the valve stem 2'to the adjusting screw 15 'continuously acts, the adjusting screw 15' rotates to a position where the minimum value of the fluctuating load becomes zero. While retreating in the axial direction, it acts to keep the valve clearance constant.

[0009]

In the lash adjuster, if the nut member 13 'is rotatable with respect to the lifter body 11', the adjusting screw 15 'can be moved in the axial direction while being rotated. Therefore, the function as a lash adjuster cannot be exerted. Therefore, the nut member 13 'is fixed to the lifter body 11'. At the time of fixing, the nut member 13 'is brazed to the lifter body 11' in the lash adjuster disclosed in Japanese Patent Laid-Open No. 11-324617. On the other hand, in the lash adjuster described in Japanese Patent Laid-Open No. 11-324618, the periphery of the nut fitting recess formed on the lower surface of the end plate 12 'is swaged.

Here, the nut member 13 'by brazing
In the case of the fixation of the nut member 13 ′, if the wax adheres to the screw hole 14 ′ of the nut member 13 ′, the screw part to which the wax is adhered is not quenched during heat treatment such as carburizing and quenching of the nut member 13 ′. However, there is a disadvantage in that it is necessary to carry out a brazing operation to prevent the wax from adhering to it, and then to carry out a heat treatment, resulting in a high processing cost.

On the other hand, when the nut member 13 'is fixed by caulking, the rotational force of the cam 1'is changed by the lifter body 11'.
However, there is a possibility that the lifter body 11 'may be deformed and the caulking may be released by repeated load, resulting in lack of reliability.

An object of the present invention is to reduce the manufacturing cost by securely locking the nut member with a simple structure in the lash adjuster using the sawtooth screw.

[0013]

In order to solve the above problems, according to the present invention, there is provided a lifter body having an end plate which is axially slidably mounted between a cam and a valve stem and which comes into contact with the cam. , A nut member provided on the lower surface of the end plate of the lifter body, an adjusting screw screwed into a screw hole of the nut member, and incorporated in the closed end of the screw hole to axially press the adjusting screw. The flank angle of the pressure side flank that receives the axial pushing load applied to the adjusting screw is made of an elastic body, and the flank angle of the play side flank is equal to that of the male thread formed on the outer circumference of the female screw of the screw hole and the outer periphery of the adjusting screw. In a lash adjuster in a valve gear having a saw tooth shape larger than a flank angle, the nut member is used as a lifter body. And assembling into contact with the end plate lower surface, it employs a configuration which is adapted to be pressed against the underside of plate by the pressing of the elastic member incorporated the nut member thereunder.

Here, as the elastic member, a plurality of engaging claws having elasticity for press-contacting and engaging with the inner peripheral surface of the lifter body are provided on the outer periphery of the annular plate portion in an inclined shape, and the inner periphery of the lifter body. It is possible to employ a disc spring or the like that is retained by a retaining ring attached to the.

As described above, the nut member is assembled so as to come into contact with the lower surface of the end plate of the lifter body, and the nut member is pressed by the elastic member incorporated therebelow to be pressed against the lower surface of the end plate. The nut member can be reliably prevented from rotating by the contact with the end plate, and the function of the lash adjuster can be reliably exhibited.

Further, as compared with the case where the nut member is fixed by means of brazing or caulking, the nut member can be assembled with less labor, and the manufacturing cost can be reduced.

In the lash adjuster according to the present invention, the lifter body and the valve stem are incorporated between the adjuster screw and the valve stem by incorporating a slide member which is prevented from rotating with respect to the nut member and movable in the axial direction. Even if is relatively rotated, the rotational force is not transmitted to the adjusting screw, and only the axial pushing force is transmitted to the adjusting screw. This axial pushing force is received by the pressure side flanks of the screw holes and the screw engaging portions of the adjusting screw, so that the adjusting screw is prevented from moving backward while rotating, and the valve lifter amount is prevented from fluctuating. You can

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a state in which a lash adjuster A _{1 according} to a first embodiment of the present invention is incorporated between a cam 1 and a valve stem 2 of a direct type valve gear.

The valve stem 2 has a spring retainer 3 at the upper end thereof, and the valve stem 2 is biased in the direction in which the valve 5 at the lower end is in close contact with the valve seat 6 by the elastic force of the valve spring 4 applied to the spring retainer 3. Has been done.

As shown in FIG. 2, the lash adjuster A
₁ has a lifter body 11 similarly to the lash adjuster shown in FIG. 7. The lifter body 11 has a guide hole 7 formed in the cylinder head B, as shown in FIG.
It is slidable inside. This lifter body 1
1 has an end plate 12 in contact with the cam 1 on the upper side, and a nut member 13 is provided below the end plate 12.

The screw hole 14 formed in the nut member 13 is closed by the end plate 12, and the adjusting screw 15 screwed into the screw hole 14 is closed by the elastic body 16 incorporated in the closed end of the screw hole 14. It is pressed in the axial direction.

With respect to the threads of the female screw 14a of the screw hole 14 and the male screw 15a formed on the outer periphery of the adjusting screw 15, the flank angle of the pressure side flank 17 which receives the pushing force applied to the adjusting screw 15 is equal to that of the play side flank 18. It has a sawtooth shape larger than the flank angle, and the sawtooth thread is provided with a lead angle for axially moving the adjusting screw 15 by the pressing of the elastic body 16.

The nut member 13 is assembled so as to contact the lower surface of the end plate 12. The nut member 13 is pressed by an elastic member 19 installed below the nut member 13 and
Is pressed against the lower surface of the plate and is prevented from rotating by contact with the end plate 12.

As shown in FIG. 3, the elastic member 19 comprises a flower retaining ring in which a plurality of elastic engaging pieces 19b are provided on the outer periphery of the annular plate portion 19a in an inclined shape. The elastic member 19 is prevented from coming off by the engagement of the engagement groove 20 formed on the inner circumference of the lifter body 11 and the engagement piece 19b.

A lash adjuster A having the above structure
_{In 1} , when the valve clearance is generated between the valve stem 2 and the adjusting screw 15 as in the lash adjuster shown in FIG. 7, the adjusting screw 15 is rotated by the pressing force of the elastic body 16 along the idle side flank 18. While moving in the axial direction, the valve clearance is absorbed.

When the adjusting screw 15 receives a pushing force by the valve stem 2, the adjusting screw 15 is retracted until the axial screw gap formed in the screw engaging portion of the female screw 14a and the male screw 15a is closed, and the pushing screw 15 is further pushed. When a force is applied, the pressure side flanks 17 that are in pressure contact with each other receive the above-mentioned pushing force and prevent the adjusting screw 15 from moving backward while rotating.

Further, in the case where the pushing load applied from the valve stem 2 to the adjusting screw 15 is a fluctuating load which continuously acts, the adjusting screw 15 rotates in the axial direction while rotating to a position where the minimum value of the fluctuating load becomes zero. It works by retracting to keep the valve clearance constant.

As shown in the embodiment, the nut member 13
Is pressed against the lower surface of the end plate 12 by the elastic member 19 incorporated therebelow, and the nut member 13 is prevented from rotating by contact with the end plate 12, whereby the nut member 13 is brazed or caulked. As compared with the case where the nut member 13 is fixed to the lifter body 11 via the means described above, the nut member 13 does not need to be assembled, and the manufacturing cost can be reduced.

FIG. 4 shows a second embodiment of the lash adjuster according to the present invention. The lash adjuster A ₂ shown in this embodiment is shown in that the elastic member 19 is prevented from coming off by engaging the tip edge of the engaging piece 19b of the elastic member 19 formed of a flower retaining ring with the inner peripheral surface of the lifter body 11. It is different from the lash adjuster A ₁ shown in 2.

Therefore, the same parts as those of the lash adjuster A ₁ shown in FIG.

In the lash adjuster A ₂ shown in the second embodiment, since it is not necessary to form the engaging groove 20 shown in FIG. 2 on the inner peripheral surface of the lifter body 11, the inner peripheral surface of the lifter body 11 can be formed. The cutting process becomes easy, and the manufacturing cost can be further reduced.

FIG. 5 shows a third embodiment of the lash adjuster according to the present invention. The lash adjuster A ₃ shown in this embodiment is a C-shaped snap ring in which the nut member 13 is pressed against the lower surface of the end plate 12 by an elastic member 21 formed of a disc spring, and the elastic member 21 is attached to the inner peripheral surface of the lifter body 11. It is different from the lash adjuster A ₁ shown in FIG.

Therefore, the same parts as those of the lash adjuster A ₁ shown in FIG.

In the lash adjuster A ₃ shown in the third embodiment, since the disc spring is adopted as the elastic member 21, the nut member 13 can be pressed against the lower surface of the end plate 12 extremely strongly, and the nut member 13 can be pressed. Can be stopped more reliably.

FIG. 6 shows a fourth embodiment of the lash adjuster according to the present invention. In the lash adjuster A ₄ shown in this embodiment, a cylindrical portion 13a is provided on the lower peripheral portion of the nut member 13, and the lower surface of the cylindrical portion 13a is pressed by an elastic member 19 composed of a flower retaining ring, and the elastic member 19 and the nut member It differs from the lash adjuster A ₂ of the second embodiment shown in FIG. 4 in that a slide member 23 and a spring 24 that presses the slide member 23 and the nut member 13 in opposite directions are incorporated between the slide member 23 and the slide member 23.

Therefore, the same parts as those of the lash adjuster A ₂ of the second embodiment are designated by the same reference numerals and the description thereof will be omitted.

Here, the slide member 23 is composed of a plurality of protruding pieces 2.
5 on the outer periphery, each protrusion 25 is fitted into each of a plurality of notches 26 formed at the lower end of the cylindrical portion 13a of the nut member 13, and the fitting causes the slide member 23 to the nut member 13. It is prevented from rotating and is movable in the axial direction.

A frustoconical bulge 27 is formed at the center of the upper surface of the slide member 23. The bulge 27 is flush with the inner surface of a conical recess 28 formed in the lower end surface of the adjusting screw 15. Are in contact.

A lash adjuster A having the above structure
₄ is assembled so that the cam 1 shown in FIG. 1 contacts the upper surface of the end plate 11 and the upper end of the valve slam 2 contacts the lower surface of the slide member 23.

In the valve train shown in FIG. 1, when the lifter body 11 receives a rotational force due to the contact with the cam 1 due to the relative displacement of the cam 1 and the lifter body 11 or the like, the lifter body 11 rotates. There is. Further, independently of this, the valve 5 and the valve stem 2 may also rotate depending on operating conditions. When these rotations occur, torque is applied to the adjusting screw 15. When the rotational force is a relatively small rotational force, even if the rotational force is such that the adjusting screw 15 is moved backward, the adjusting screw 15 causes sliding rotation due to the frictional force acting on the contact portion between the pressure side flanks 17. There is no such thing.

However, if the rotational force is large, the adjusting screw 15 may slip and rotate to retract, and if the adjusting screw 15 retracts, the valve lift amount fluctuates.

As in the lash adjuster shown in the fourth embodiment, the slide member 23 is incorporated between the adjusting screw 15 and the valve stem 2, and the slide member 2 is installed.
3 is prevented from rotating with respect to the lifter body 11 and is movable in the axial direction, the rotational force is not transmitted to the adjusting screw 15 even if the lifter body 11 and the valve stem 2 rotate relative to each other. Only the pushing force into is transmitted. This pushing force is 1
4 and the adjusting screw 15 are received by the pressure side flank 17 in the screw engaging portion of the adjusting screw 15.
5 does not retract in the axial direction. Therefore, the valve lift amount does not vary, and a constant valve lift amount can be obtained.

In the fourth embodiment, in order to prevent the slide member 23 from rotating within the range of the play between the nut member 13 and the slide member 23 in the rotation direction, the spring 24 makes the slide member 23 elastic. Although the slide member 23 is pressed against 19 to prevent the slide member 23 from rotating, the spring 24 may be omitted if the valve lift amount when the slide member 23 rotates within the play is within the allowable range. .

[0044]

As described above, in the present invention, the nut member is assembled so as to come into contact with the lower surface of the end plate of the lifter body, and the nut member is pressed by the elastic member provided therebelow to lower the lower surface of the end plate. By contacting the nut member, the nut member can be prevented from rotating. Therefore, the nut member can be easily stopped as compared with the case where the nut member is fixed by brazing or caulking to prevent rotation.
It is possible to reduce the manufacturing cost of the lash adjuster.

[Brief description of drawings]

FIG. 1 is a vertical sectional front view of a valve train incorporating a lash adjuster according to the present invention.

FIG. 2 is an enlarged sectional view of the lash adjuster shown in FIG.

FIG. 3 is a perspective view of an elastic member that presses a nut member of the lash adjuster shown in FIG.

FIG. 4 is a vertical sectional front view showing a second embodiment of the lash adjuster according to the present invention.

FIG. 5 is a vertical sectional front view showing a third embodiment of the lash adjuster according to the present invention.

FIG. 6 is a vertical sectional front view showing a fourth embodiment of the lash adjuster according to the present invention.

FIG. 7 is a vertical sectional front view of a valve train including a conventional lash adjuster.

[Explanation of symbols]

1 cam 2 valve stem 11 Lifter body 12 End plate 13 Nut member 14 screw holes 15 Adjust screw 16 Elastic body 17 Pressure flank 18 Play side Frank 19 Elastic member 19a annular plate part 19b Engagement piece 21 Elastic member 22 retaining ring 23 Slide member

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Claims (4)

[Claims] 1. A lifter body which is slidably incorporated between a cam and a valve stem in an axial direction and has an end plate in contact with the cam at an upper portion, a nut member provided on a lower surface of the end plate of the lifter body, and a nut member thereof. Formed on the outer circumference of the female screw and the adjustment screw of the screw hole, and an elastic body that is incorporated in the closed end of the screw hole to press the adjust screw in the axial direction. The thread of the male screw
In a lash adjuster in a valve gear in which the flank angle of the pressure side flank that receives an axial pushing load applied to the adjusting screw is larger than the flank angle of the idle side flank, in the lash adjuster, the nut member is placed on the lower surface of the end plate of the lifter body. A lash adjuster in a valve operating system, characterized in that the nut member is brought into contact with the lower surface of the end plate by pressing an elastic member incorporated below the nut member. 2. The flower-shaped retaining ring according to claim 1, wherein the elastic member is provided with a plurality of engaging claws, which have elasticity and are in elastic contact with the inner peripheral surface of the lifter body, on the outer periphery of the annular plate portion. Lash adjuster in the valve gear of the. 3. The lash adjuster for a valve train according to claim 1, wherein the elastic member is a disc spring that is retained by a retaining ring attached to the inner circumference of the lifter body. 4. A valve operating system according to claim 1, wherein a slide member which is fixed to the nut member and is movable in the axial direction is incorporated between the adjuster screw and the valve stem. Rush adjuster.